Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and...Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and subsequent Sb accumulation in rice.Here,the effects of NO3^(-)on Sb transformation in soil-rice system were investigated with pot experiments over the entire growth period.Results demonstrated that NO3^(-)reduced Sb accumulation in brown rice by 15.6%compared to that in the control.After amendment with NO3^(-),the Sb content in rice plants increased initially and then gradually decreased(in roots by 46.1%).During the first 15 days,the soil p H increased,the oxidation of Sb(Ⅲ)and sulfides was promoted,but the reduction of iron oxide minerals was inhibited,resulting in the release of adsorbed and organic-bound Sb from soil.The microbial arsenite-oxidizing marker gene aox B played an important role in Sb(Ⅲ)oxidation.From days 15 to 45,after NO3^(-)was partially consumed,the soil p H decreased,and the reductive dissolution of Fe(Ⅲ)-bearing minerals was enhanced;consequently,iron oxide-bound Sb was transformed into adsorbed and dissolved Sb species.After day 45,NO3^(-)was completely reduced,Sb(V)was evidently reduced to Sb(Ⅲ),and green rust was generated gradually.Thus,the available Sb decreased due to its enhanced affinity for iron oxides.Moreover,NO3^(-)inhibited the reductive dissolution of iron minerals,which ultimately caused low Sb availability.Therefore,NO3^(-)can chemically and biologically reduce the Sb availability in paddy soils and alleviate Sb accumulation inrice.This study provides a potential strategy for decreasing Sb accumulation in rice in the Sb-contaminated sites.展开更多
基金the National Key Research and Development Program of China(Nos.2017YFD0801002,2018YFF0213403)GDAS’Project of Science and Technology Development(No.2020GDASYL-20200103076)China Postdoctoral Science Foundation(No.2019M652834)。
文摘Nitrate(NO3^(-))is known to be actively involved in the processes of mineralization and heavy metal transformation;however,it is unclear whether and how it affects the bioavailability of antimony(Sb)in paddy soils and subsequent Sb accumulation in rice.Here,the effects of NO3^(-)on Sb transformation in soil-rice system were investigated with pot experiments over the entire growth period.Results demonstrated that NO3^(-)reduced Sb accumulation in brown rice by 15.6%compared to that in the control.After amendment with NO3^(-),the Sb content in rice plants increased initially and then gradually decreased(in roots by 46.1%).During the first 15 days,the soil p H increased,the oxidation of Sb(Ⅲ)and sulfides was promoted,but the reduction of iron oxide minerals was inhibited,resulting in the release of adsorbed and organic-bound Sb from soil.The microbial arsenite-oxidizing marker gene aox B played an important role in Sb(Ⅲ)oxidation.From days 15 to 45,after NO3^(-)was partially consumed,the soil p H decreased,and the reductive dissolution of Fe(Ⅲ)-bearing minerals was enhanced;consequently,iron oxide-bound Sb was transformed into adsorbed and dissolved Sb species.After day 45,NO3^(-)was completely reduced,Sb(V)was evidently reduced to Sb(Ⅲ),and green rust was generated gradually.Thus,the available Sb decreased due to its enhanced affinity for iron oxides.Moreover,NO3^(-)inhibited the reductive dissolution of iron minerals,which ultimately caused low Sb availability.Therefore,NO3^(-)can chemically and biologically reduce the Sb availability in paddy soils and alleviate Sb accumulation inrice.This study provides a potential strategy for decreasing Sb accumulation in rice in the Sb-contaminated sites.
